System and assembly having conductive fixation features

ABSTRACT

A lead having a distal end electrode assembly adapted for implantation on or about the heart or within a vein and for connection to a system for monitoring or stimulating cardiac activity. The electrode assembly includes conductive fixation features, such as conductive tines or flexible members, in combination with non-conductive fixation features. The conductive fixation features also include tines coated with a conductive material. The fixation features further include conductive tines which are retractable. A defibrillation coil is optionally disposed at the distal end of the lead in combination with the conductive tines.

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application is a division of U.S. patent application Ser.No. 09/746,614, filed on Dec. 21, 2000, which is a division of U.S.patent application Ser. No. 09/349,266, filed on Jul. 7, 1999, nowabandoned, the specifications of which are incorporated by referenceherein.

FIELD OF THE INVENTION

[0002] The present invention relates generally to leads for conductingelectrical signals to and from the heart. More particularly, it pertainsto an electrode having conductive fixation features for deliveringelectrical charges to and from the heart.

BACKGROUND OF THE INVENTION

[0003] Cardiac rhythm systems are used for treating an irregular orunstable heart. The systems include, among other things, pacemakerswhich deliver timed sequences of low electrical energy to the heart,such as via a lead having one or more electrodes. Leads have beenimplanted in the body for electrical cardioversion or pacing of theheart. More specifically, electrodes implanted in or about the hearthave been used to reverse (i.e., defibrillate or cardiovert) or sensecertain life threatening arrhythmias, or to stimulate contraction(pacing) of the heart, where electrical energy is applied to the heartvia the electrodes to return the heart to normal rhythm.

[0004] Cardiac pacing and/or sensing may be performed by the transvenousmethod or by electrodes implanted directly onto the epicardium.Traditionally, to attach a lead epicardially, a thoracotomy is performedwhere the thorax is opened to obtain access to the heart. This procedureinvolves painful and expensive surgery for the patient. Transvenouspacing may be temporary or permanent. In temporary transvenous pacing anelectrode catheter is introduced into a peripheral vein andfluoroscopically positioned against the endocardium.

[0005] Traditional permanent transvenous pacing is performed understerile surgical conditions where an electrode is positioned in theventricle or atrium through a subclavian vein, and the proximalterminals are attached to a pulse generator which is implantedsubcutaneously. The distal tip of the lead is positioned within an apexof the heart to hold the lead in place. Leads which are implanted in theapex of the heart have a backstop, which assists in preventing the leadfrom floating, and allows for the distal end of the lead to becomefixated therein. Potential complications induced by the presence of thelead within the chambers of the heart, however, can preclude leadimplantation of the lead within the chambers of the heart.

[0006] One approach to resolve this issue is to implant the leadtransvenously. When a lead is implanted transvenously, the passage hasno termination into which the lead can be positioned, resulting in afloating lead. One of the drawbacks of a floating lead is that theperformance of the electrical interface between the electrode and thetissue can be diminished. In addition, the veins or arteries are filledwith blood, surrounding the electrode, which further inhibits theelectrical interface between the electrode and the tissue.

[0007] Defibrillation, which is used to treat a heart which is beatingtoo quickly, delivers a high energy electrical stimulus which allows theheart to reestablish a normal rhythm. In addition to a defibrillatingelectrode can be combined with a pacing and/or sensing electrode. Toobtain lower pacing and sensing thresholds, the pacing/sensing electrodeis traditionally disposed at the tip of the lead, which is positioneddeep within an apex of the heart at the largest center of mass of theheart. To minimize sensing problems following a shock from thedefibrillating electrode, the defibrillating electrode is separated awayfrom the sensing/pacing electrode on the lead. As the defibrillatingelectrode is moved away from the tip of the lead, however, the shockstrength requirement increases resulting in increased demands on thebattery of the cardiac rhythm system.

[0008] Accordingly, there is a need for an implantable lead that iscapable of placement and fixation in other regions of the heart, such aswithin vascular structures. In addition, there is a need for a leadhaving an electrode for positioning within a passage, such as a vein orartery, that allows for fixation of the lead. There is also a need for abody implantable lead which allows for effective stimulation from adefibrillation electrode. There is further a need for a lead that iscapable of effectively defibrillating the heart, and also pacing/sensingthe heart in a limited area.

SUMMARY OF THE INVENTION

[0009] The present invention relates to a lead assembly having a leadbody extending from a distal end to a proximal end, and includes aconductor. The lead assembly further includes an electrode assembly ofat least one electrode, and the electrode assembly is electricallycoupled with the conductor. The electrode assembly has an electricallyconductive tine adapted for fixating the lead assembly within tissue. Inone embodiment, the tine has a first end coupled with the lead body anda second end which extends away from the lead body.

[0010] In another embodiment, the tine is formed of an electricallyconductive material, for instance, conductive silicone. In anotherembodiment, the conductive tine includes a conductive coating. In yetanother embodiment, the conductive tine is molded to the conductor. Theconductive tine further optionally includes one or more non-conductivetines adapted for fixating a portion of the lead assembly. In addition,a defibrillation electrode is disposed at the distal end of the leadbody in another embodiment.

[0011] In one embodiment, the lead assembly, which has a lead bodyextending from a distal end to a proximal end, includes a conductor. Thelead assembly further includes an electrode assembly of at least oneelectrode, and the electrode assembly is electrically coupled with theconductor. The electrode assembly has an electrically conductive coneadapted for fixating the lead assembly within tissue. In one embodiment,the cone includes a conductive ring disposed on a distal end of thecone.

[0012] In another embodiment, a lead assembly has a lead body extendingfrom a distal end to a proximal end, and includes a conductor. The leadassembly further includes an electrode assembly of at least oneelectrode, and the electrode assembly is electrically coupled with theconductor. The electrode assembly has an electrically conductive tineadapted for fixating the lead assembly within tissue. A conductivemember is disposed within a portion of the conductive tine and iselectrically coupled with the electrode assembly.

[0013] In one embodiment, the conductive tine includes a partial coatingof non-conductive material. In another embodiment, a plurality ofconductive tines are provided. The conductive member, in one embodiment,is a wire. In another embodiment, the conductive member is a flat wireor a foil. In yet another embodiment, the conductive tine extends from afirst end proximate to the lead body to a second end disposed away fromthe lead body, and a conductive cap is at the second end of theconductive tine.

[0014] In another embodiment, a lead assembly is disclosed which has alead body extending from a distal end to a proximal end, and includes aconductor. An intermediate portion of the lead body has a straight leadbody. The lead assembly further includes a conductive fixation featurewhich extends away from the lead body. The conductive fixation featureis a protrusion which extends from the intermediate portion of the leadbody, and includes an electrode. In one embodiment, the electrode is asensing or pacing electrode. In another embodiment, the conductivefixation feature is a conductive tine. In addition, the tine includes acap coupled with the tine in another embodiment. In yet anotherembodiment, a non-conductive tine is coupled with the lead body and isadapted for fixating a portion of the lead assembly within tissue.

[0015] In yet another embodiment, a lead assembly has a lead bodyextending from a distal end to a proximal end, and includes a conductor.A defibrillation electrode is electrically coupled with the conductor,and is disposed at a second end of the conductor forming adefibrillation tip at the distal end of the lead body. The lead assemblyfurther includes, in another embodiment, a second defibrillation coildisposed at an intermediate portion of the lead body. In addition, thelead assembly includes an electrically conductive tine coupled with aportion of the lead body, in one embodiment. The conductive tineoptionally has a first end coupled with the lead body and a second endwhich extends away from the lead body. In another embodiment, theconductive tine is partially covered with non-conductive material. Aconductive bead, in one embodiment, is coupled with a distal end of theconductive tine. In another embodiment, the tine is electrically commonwith the defibrillation electrode. An electrical discharge surface, in afurther embodiment, is disposed between the second defibrillation coiland the distal defibrillation tip, where insulation is optionallydisposed between the conductive tine and the defibrillation coil.

[0016] A lead assembly, in another embodiment, has a lead body extendingfrom a distal end to a proximal end, and includes a conductor. The leadassembly further includes an electrode assembly of at least oneelectrode, and the electrode assembly is electrically coupled with theconductor. The electrode assembly has a plurality of electricallyconductive tines adapted for fixating the lead assembly within tissue,and the conductive tines are retractable. In one embodiment, the tineshave a first end extending from a hinge point and a second end whichextends away from the hinge point, where the conductive tine flex at thehinge point. In a retracted position, the retractable tines are disposedin a lumen of the lead body. In an extended position, the retractabletines are extended out of the lumen.

[0017] In another embodiment, a lead assembly has a lead body extendingfrom a distal end to a proximal end, and includes a conductor. The leadassembly further includes an electrically conductive fitting coupledwith the conductor. An electrode assembly is coupled with the fitting.The electrode assembly including an electrically conductive tine isadapted for fixating the lead assembly within tissue and is molded tothe fitting. In one embodiment, the tine is formed of a conductivepolymer. In another embodiment, the tine is formed of a conductiverubber or elastomer.

[0018] In yet another embodiment, a lead assembly has a lead bodyextending from a distal end to a proximal end, and includes a conductor.The lead assembly further includes an electrode assembly of at least oneelectrode, and the electrode assembly is electrically coupled with theconductor. The electrode assembly has a conductive fixation featurewhich is adapted to send and receive electrical signals. The conductivefixation feature extends from a first end to a second end and includes aflexible and conductive intermediate portion between the first end andthe second end. The intermediate portion is flexible away from theconductor. In one embodiment, the first end of the conductive fixationfeature is coupled with the lead body and the second end is movablycoupled with the lead body. The lead assembly further includes, inanother embodiment, a locking mechanism adapted to maintain theintermediate portion in a flexed position. In another embodiment, thelocking mechanism includes a slider movably disposed within a slot, andan interference slot sized to engage the slider. The slider is coupledwith the second end of the conductive fixation feature. The leadassembly further includes a deployment mechanism, in another embodiment.Examples of deployment mechanisms include a wire or a balloon catheter.

[0019] Another embodiment is a lead assembly which has a lead bodyextending from a distal end to a proximal end, and includes a conductor.The lead assembly further includes an electrode assembly of at least oneelectrode, and the electrode assembly is electrically coupled with theconductor. A sheath of conductive material is disposed over theelectrode assembly. The sheath, in one embodiment, is formed of aconductive polymer. In another embodiment, the sheath is formed of aconductive urethane. In one embodiment, the electrode assembly comprisesa defibrillation coil.

[0020] In yet another embodiment, a system for delivering signals to theheart includes an electronics system including a cardiac activity sensorand a signal generator for producing signals to stimulate the heart, anda lead assembly. The lead assembly has a lead body extending from adistal end to a proximal end, and includes a conductor. The leadassembly further includes an electrode assembly of at least oneelectrode, and the electrode assembly is electrically coupled with theconductor. The electrode assembly has an electrically conductive tineadapted for fixating the lead assembly within tissue. The tine has afirst end coupled with the lead body and a second end which extends awayfrom the lead body. In one embodiment, the tine is formed of aconductive polymer. In another embodiment, the tine is formed of aconductive polymer, rubber, or elastomer. The conductive tine, in oneembodiment, includes a conductive coating. In yet another embodiment,the conductive tine is molded to the conductor. The conductive tinefurther optionally includes one or more non-conductive tines adapted forfixating a portion of the lead assembly. In yet another embodiment, theconductive tine is a wire extending away from the lead body.

[0021] These and other embodiments, aspects, advantages, and features ofthe present invention will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the art byreference to the following description of the invention and referenceddrawings or by practice of the invention. The aspects, advantages, andfeatures of the invention are realized and attained by means of theinstrumentalities, procedures, and combinations particularly pointed outin the appended claims and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 illustrates a system for monitoring and stimulating theheart constructed in accordance with one embodiment.

[0023]FIG. 2 is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0024]FIG. 3 is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0025]FIG. 4A is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0026]FIG. 4B is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0027]FIG. 5 is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0028]FIG. 6 is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0029]FIG. 7 is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0030]FIG. 8A is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0031]FIG. 8B is a side elevational view of the electrode assembly shownin FIG. 8A.

[0032]FIG. 9 is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0033]FIG. 10 is a side elevational view of an electrode assemblyconstructed in accordance with one embodiment.

[0034]FIG. 11A illustrates a system for monitoring and stimulating theheart constructed in accordance with one embodiment.

[0035]FIG. 11B illustrates a system for monitoring and stimulating theheart constructed in accordance with one embodiment.

[0036]FIG. 12 is a cross-section of an electrode assembly constructed inaccordance with one embodiment.

[0037]FIG. 13 is an end view of the electrode assembly shown in FIG. 12.

[0038]FIG. 14A is a cross-section of an electrode assembly constructedin accordance with one embodiment.

[0039]FIG. 14B is an end view of the electrode assembly shown in FIG.14A.

[0040]FIG. 15 is a cross-section of a portion of a lead constructed inaccordance with one embodiment.

[0041]FIG. 16A is a cross-section of a portion of a lead constructed inaccordance with one embodiment.

[0042]FIG. 16B is a cross-section of a portion of a lead constructed inaccordance with one embodiment.

[0043]FIG. 17A is a cross-section of a portion of a lead constructed inaccordance with one embodiment.

[0044]FIG. 17B is a cross-section of a portion of a lead constructed inaccordance with one embodiment.

DESCRIPTION OF THE EMBODIMENTS

[0045] In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that structuralchanges may be made without departing from the spirit and scope of thepresent invention. Therefore, the following detailed description is notto be taken in a limiting sense, and the scope of the present inventionis defined by the appended claims and their equivalents.

[0046]FIG. 1 illustrates a lead 100 for delivering electrical pulses tostimulate the heart 110 and/or for receiving electrical pulses tomonitor the heart 110. The lead 100 has a distal end 102 adapted forconnection within a patient and a proximal end 104. The proximal end 104has a terminal connector which electrically connects the variouselectrodes and conductors within the lead body to a pulse generator 120and signal sensor. The terminal connector provides for the electricalconnection between the lead 100 and the pulse generator 120. The pulsesensor and generator 120 contains electronics to sense variouselectrical signals of the heart 110 and also produce current pulses fordelivery to the heart 110. The pulse sensor and generator 120 alsocontains electronics and software necessary to detect certain types ofarrhythmias and to correct for them.

[0047] The lead 100 includes a lead body 115, an elongate conductor 116contained within the lead body 115, and at least one electrode assembly130. In one embodiment, the electrode assembly 130 is disposed proximateto the distal end 102 of the lead 100. In another embodiment, theelectrode assembly 130 is disposed between the distal end 102 and theproximal end 104 of the lead 100, at an intermediate portion 103 of thelead 100. The lead body 115 is covered by a biocompatible insulatingmaterial. Silicone rubber or other insulating material is used forcovering the lead body 115.

[0048] The conductor 116 comprises, in one embodiment, a coil. Aconductor coil is capable of withstanding constant, rapidly repeatedflexing. The coiled construction is wound relatively tightly providing amaximum number of conductor turns per unit length, which allows forstrain distribution. The spirally coiled spring construction of theconductor also permits a substantial degree of elongation, within theelastic limits of the material, as well as distribution along theconductor of flexing stresses which otherwise might be concentrated at aparticular point.

[0049] The elongate conductor 116 defines a lumen therein and thereby isadapted to receive a stiffening stylet that extends through the lengthof the lead 100. The stylet stiffens the lead 100, and can bemanipulated to introduce an appropriate curvature to the lead 100. Themanipulation of the stylet facilitates the insertion of the lead 100into and through a vein and through an intracardiac valve to advance thedistal end 102 of the lead 100 into, for example, the right ventricle ofthe heart. A stylet knob is coupled with the stylet for rotating thestylet, advancing the conductor into tissue of the heart, and formanipulating the lead 100.

[0050] The electrode assembly 130 is adapted to be coupled with tissueof a patient, for example, within a heart 110 or in a vein 210, asillustrated in FIG. 2. In one embodiment, an electrode assembly 230includes at least one electrically conductive tine 220 which is coupledwith a lead 200. The tine 220 is, in one embodiment, disposed through alead body 215 and is coupled with a conductor 216, as further discussedbelow. The tine 220 is adapted to send and receive electrical signalswithin a patient, serving as an electrode, and also assists in fixatingthe lead 200 within a patient. The tine 220, in one embodiment,comprises a slender projection which projects from the lead body 215 atan angle of less than 90 degrees. In another embodiment, the tine 220 isdisposed substantially traverse to the lead body 215 prior to and/orduring installation within, for instance, a vein or an artery. In oneembodiment, the tine 220 comprises an angled projection disposed on astraight portion 229 of the lead body 215.

[0051] The tine 220 comprises a conductive element formed of aconductive material, for example, a metal wire. Alternatively, inanother embodiment, the tine 220 is formed of a flat wire or a foil. Thetine 220 is electrically coupled with a conductor coil 216, forinstance, by welding. In addition, the tine 220 is coupled with tissueor within the wall of the vein 210 such that the tine 220 can send andreceive signals to and from the pulse sensor and generator. The tine 220is adapted to sense and/or pace when the lead 200 is implanted into apatient. In another embodiment, the tine 220 is formed of a semi-rigidmaterial, such as wire, and assists in fixating the lead 200 withintissue, for example, a vein 210.

[0052]FIG. 3 illustrates another embodiment of a lead 300. The lead 300includes a plurality of electrically conductive tines 320 which arecoupled with the lead 300. In one embodiment, the conductive tines 320are electrically coupled with a conductor 316, and are adapted to sendand receive electrical signals within a patient, as discussed in theembodiment illustrated in FIG. 2. In this embodiment, the conductivetines 320 function as an electrode. In another embodiment, theconductive tines 320 are coupled with an electrode 302 which is disposedon the lead body 315, such as a ring electrode. The conductive tines 320and the electrode 302 work together to send and receive electricalsignals within a patient. The conductive tines 320, in yet anotherembodiment, comprise slender projections which project from the leadbody 315.

[0053] The conductive tines 320 comprise conductive elements formed of aconductive material, for example, metal wires. Alternatively, in anotherembodiment, the conductive tines 320 are formed of flat wires or foils.The conductive tines 320 are electrically coupled with conductor coil316, for instance, by welding. The conductive tines 320 are also coupledwith tissue or within the wall of the vein to facilitate sending andreceiving signals between the patient and the pulse sensor andgenerator.

[0054] In another embodiment, the lead 300 also includes non-conductivetines 340. The non-conductive tines 340 are formed of a non-conductivematerial, for example, a polymer. The non-conductive tines 340 arecoupled with the lead body 315 and further assist in fixating the lead300 within a heart, a vein, or other location within a patient. In oneembodiment, the non-conductive tines 340 comprise slender projectionswhich extend away from the lead body 315, for instance, at an angle. Inanother embodiment, the tines 340 are conductive.

[0055]FIGS. 4A and 4B illustrate yet another embodiment of a lead 400.In one embodiment, an electrode assembly 430 includes a plurality ofconductive tines 420, or optionally a single conductive tine, which arecoupled with a lead 400. The conductive tines 420 are coupled with aconductor 416, as further discussed below. The conductive tines 420 areadapted to send and receive electrical signals within a patient, servingas an electrode, and also assists in fixating the lead 400 within apatient. The conductive tines 420 are adapted to sense and/or pace whenthe lead 400 is implanted into a patient.

[0056] The conductive tines 420 comprise conductive elements formed of aconductive material, for example, a metal wire. Alternatively, inanother embodiment, the conductive tines 420 are formed of a flat wireor a foil. In another embodiment, the tines 420 is formed of asemi-rigid material, such as wire, and assists in fixating the lead 400within tissue, for example, a vein. The conductive tines 420 areelectrically coupled with a conductor coil 416, for instance, bywelding. In addition, the conductive tines 420 extend from a hinge point422 to a distal end 424 for each tine. The conductor 416 is coupled withthe conductive tines 420 proximate to the hinge point 422, and theconductive tines 420 are adapted to flex at the hinge point 422.

[0057] During implant of the lead 400 or when the conductive tines 420are not in use, the conductive tines 420 are retracted toward theconductor coil 416. The retracted conductive tines 420 are disposedwithin a lumen 418 of the lead 400 in a recessed position, as shown inFIG. 4A. The conductive tines 420, when disposed within the lead 400,are spring-loaded such that the tines 420 expand away from the conductorcoil 416 when the conductive tines 420 are outside of the lead 400. Toinstall the conductive tines 420 from the recessed position of FIG. 4A,force is exerted on the conductor coil 416 to push the retractedconductive tines 420 out of the lead 400. Alternatively, othermechanisms, such as a stylet, are used to extend the conductive tines420 from the recessed position.

[0058] When the conductive tines 420 are extended out of lumen 418 ofthe lead 400, as shown in FIG. 4B, the conductive tines 420 expand awayfrom the conductor coil 416, for example, by the force of a spring.After the conductive tines 420 are expanded, the conductive tines 420are in position to engage with tissue, such as within a vein. Theconductor tines 420 are expandable and retractable, which allows for thetines 420 to be used in conjunction with, or in alternative to, otherelectrodes, providing increased flexibility before or after the lead 400has been implanted into a patient.

[0059] In another embodiment, the lead 400 also includes non-conductivetines 440. The non-conductive tines 440 are formed of a non-conductivematerial, for example, a polymer. The non-conductive tines 440 arecoupled with the lead body 415 and further assist in fixating the lead400 within a heart, a vein, or other location within a patient. In oneembodiment, the non-conductive tines 440 comprise slender projectionswhich extend away from the lead body 415, for instance, at an angle.

[0060]FIG. 5 illustrates another embodiment of a lead 500, whichincludes at least one electrically conductive tine 520 coupled with thelead 500, and is electrically coupled with a conductor coil 516. Theconductive tine 520 is adapted to send and receive electrical signalswithin a patient such that the conductive tine 520 serves as anelectrode. The conductive tine 520 also assists in fixating the lead 500within a patient, for instance, within a vein. The conductive tine 520,in one embodiment, comprises a slender projection which projects fromthe lead body 515.

[0061] The conductive tine 520, in one embodiment, is molded directly tothe conductor coil 516, and is electrically coupled thereto. In oneembodiment, the conductive tine 520 forms a portion 521 of the lead body515, which increases the sensing and/or pacing area of the conductivetine 520. Alternatively, in another embodiment, the conductive tine 520is formed as a separate component, and is coupled with the conductorcoil 516 and the lead body 515. The lead body 515 is formed ofnon-conductive material and insulates the conductive tine 520 which ismolded on to, or otherwise formed on or within the lead body 515. Inanother embodiment, the conductive tine 520 is formed of a conductivematerial, for example, using a conductive polymer. Suitable materialsfor molding or otherwise forming the conductive tine 520 include, butare not limited to: conductive polymers, rubbers, or elastomers likeconductive silicone rubber and conductive thermoplastic elastomers likepolyurethane elastomers, polyether-ester elastomers, and polyether-amideelastomers. As mentioned above, the conductive tine 520 is electricallycoupled with the conductor coil 516. In addition, the tine 520 iscoupled with tissue or within the wall of a vein such that the tine 520can send and receive signals to and from the pulse sensor and generator.

[0062] In another embodiment, as illustrated in FIG. 6, a lead 600includes at least one electrically conductive tine 620, which is coupledwith the lead 600 and electrically coupled with a conductor coil 616 ofthe lead 600. The conductive tine 620 is adapted to send and receiveelectrical signals within a patient, such that the conductive tine 620serves as an electrode. The conductive tine 620 also assists in fixatingthe lead 600 within a patient, for instance, within a vein. Theconductive tine 620, in one embodiment, comprises a slender projectionwhich projects from the lead body 615.

[0063] A fitting 622 is electrically coupled with the conductor coil616, for instance, by welding the fitting 622 to the conductor coil 616.Alternatively, the fitting 622 is electrically coupled with theconductor coil 616 using conductive adhesive. The fitting 622 is formedfrom a conductive material, such as stainless steel or other conductivemetals. The conductive tine 620, in one embodiment, is molded to thefitting 622, and is electrically coupled thereto. Alternatively, inanother embodiment, the conductive tine 620 is formed as a separatecomponent, and is coupled with the fitting 622 and the lead body 615. Inone embodiment, the fitting 622 includes a series of holes 670 which areformed through the fitting 622. The holes 670 allow for the conductivematerial forming the conductive tine 620 to therethrough, therebyallowing for attachment of the conductive tine 620 to the fitting 622.

[0064] The lead body 615 is formed of non-conductive material andinsulates a portion of the conductive tine 620 which is molded on to, orotherwise formed on or within the lead body 615. In another embodiment,the conductive tine 620 is formed of a conductive material, for example,using a conductive polymer. In yet another embodiment, the conductivetine 620 is formed of a flexible material. Suitable materials formolding or otherwise forming the conductive tine 620 include, but arenot limited to: conductive polymers, rubbers, or elastomers likeconductive silicone rubber and conductive thermoplastic elastomers likepolyurethane elastomers, polyether-ester elastomers, and polyether-amideelastomers. As mentioned above, the conductive tine 620 is electricallycoupled with the fitting 622 and the conductor coil 616. In addition,the tine 620 is coupled with tissue or within the wall of a vein suchthat the tine 620 can send and receive signals to and from the pulsesensor and generator.

[0065]FIG. 7 illustrates yet another embodiment of a lead 700 whichincludes at least one conductive tine 720. The conductive tine 720 iscoupled with the lead 700 and electrically coupled with a conductor coil716. The conductive tine 720 is adapted to send and receive electricalsignals within a patient, the conductive tine 720 serving as anelectrode, or supplementing another electrode. The conductive tine 720also assists in fixating the lead 700 within a patient, for instance,within a vein. The conductive tine 720, in one embodiment, comprises aslender projection which projects from the lead body 715. Afterimplanting the lead 700, the conductive tine 720 assists in mechanicallyfixating the lead 700 within tissue.

[0066] The conductive tine 720, in one embodiment, is molded to orwithin the lead body 715, and is coated with a conductive coating 721.The conductive coating 721 is electrically coupled with the conductorcoil 716, for instance by a wire 718 or another conductive element.Suitable materials for the conductive coating 721 include, but are notlimited to: conductive polymers, rubbers, or elastomers like conductivesilicone rubber and conductive thermoplastic elastomers likepolyurethane elastomers, polyether-ester elastomers, and polyether-amideelastomers. The lead body 715 is formed of non-conductive material andinsulates the conductive tine 720 and also the conductor coil 716.

[0067] In another embodiment, a lead 800 is provided with at least oneconductive tine 820, as illustrated in FIGS. 8A and 8B. The tine 820 is,in one embodiment, coupled with a lead body 815 and is electricallycoupled with a conductor coil 816, as further discussed below. The tine820 is adapted to send and receive electrical signals within a patient,serving as an electrode, or supplements the pacing or sensing of anotherelectrode. In addition, the conductive tine 820 assists in fixating thelead 800 within a patient.

[0068] The tine 820, in one embodiment, comprises a slender projectionwhich projects from the lead body 815 at an angle. The tine 820 includesnon-conductive material 827, and an exposed portion as further discussedbelow. Disposed within the tine 820 is a conductive element 821 formedof a conductive material, for example, a metal wire. Alternatively, inanother embodiment, the conductive element 821 is formed of a flat wireor a foil. The conductive element 821 is electrically coupled with aconductor coil 816, for instance, by welding or by conductive adhesive.The non-conductive material 827 partially covers the conductive element821. A portion 823 of the conductive element 821 is exposed, allowingfor the portion 823 to be exposed to tissue. Referring to FIG. 8B, theportion 823 which is exposed can be in a variety of shapes and sizes. Inone embodiment, the exposed portion 823 of the conductive element 821 issquare shaped.

[0069]FIG. 9 illustrates another embodiment of a lead 900 with at leastone conductive tine 920. The tine 920 is, in one embodiment, coupledwith a lead body 915 and is electrically coupled with a conductor coil916, as further discussed below. The tine 920 is adapted to send andreceive electrical signals within a patient, such that the at least oneconductive tine 920 serves as an electrode, or supplements the pacing orsensing of another electrode. In addition, the conductive tine 920assists in fixating the lead 900 within a patient.

[0070] The tine 920, in one embodiment, comprises a slender projectionwhich projects from the lead body 915. A conductive cap 930 is disposedon a distal end 926 of the tine 920. It should be noted, however, thatthe conductive cap 930 can be disposed on other portions of the tine920. In one embodiment, the conductive cap 930 is coupled with the tine920. Disposed within the tine 920 is a conductive element 921 formed ofa conductive material, for example, a metal wire. Alternatively, inanother embodiment, the conductive element 921 is formed of a flat wireor a foil.

[0071] The conductive element 921 is electrically coupled with aconductor coil 916 of the lead 900, for instance, by welding, crimping,or by conductive adhesive. In addition, the conductive element 921 iselectrically coupled with the conductive cap 930, and forms theelectrical connection between the conductive cap 930 and the conductorcoil 916, which allows for the tine 920 to be conductive. The conductivecap 930 of the conductive tine 920 is adapted to contact tissue of apatient in which the lead 900 is implanted. In addition, the tine 920assists in physically fixating the lead 900 within, for instance, a veinor artery.

[0072] Another embodiment of a lead 1000 is shown in FIG. 10, whichillustrates a lead 1000 with at least one conductive fixation member1020. The fixation member 1020 is, in one embodiment, coupled with alead body 1015 and is electrically coupled with a conductor coil 1016,as further discussed below. The fixation member 1020 is adapted to sendand receive electrical signals within a patient, serving as anelectrode, or supplements the pacing or sensing of another electrode. Inaddition, the fixation member 1020 assists in fixating the lead 1000within a patient.

[0073] The fixation member 1020, in one embodiment, comprises a cone1022 which projects from the lead body 1015. The cone 1022 has a conicalshape which is disposed about the lead body 1015. A conductive ring 1030is disposed on a distal end 1026 of the fixation member 1020. It shouldbe noted, however, that the conductive ring 1030 can be disposed onother portions of the fixation member 1020. In one embodiment, theconductive ring 1030 is coupled with the fixation member 1020. Disposedwithin the fixation member 1020 is a conductive element 1021 formed of aconductive material, for example, a metal wire.

[0074] The conductive element 1021 is electrically coupled with aconductor coil 1016, for instance, by welding or by conductive adhesive.In addition, the conductive element 1021 is electrically coupled withthe conductive ring 1030, and forms the electrical connection betweenthe conductive ring 1030 and the conductor coil 1016, which allows forthe fixation member 1020 to be conductive. The conductive ring 1030 ofthe fixation member 1020 is adapted to contact tissue of a patient inwhich the lead 1000 is implanted, and allows for the conductive fixationmember 1020 to serve as an electrode. In addition, the fixation member1020 assists in physically fixating the lead 1000 within, for instance,a vein or artery of a patient.

[0075]FIG. 11A illustrates another embodiment of a lead 1100. The lead1100 has a distal end 1102 which is implanted within a body, and aproximal end 1104. The proximal end 1104 has a connector terminal whichelectrically connects the various electrodes and conductors within thelead 1100 to a pulse generator 1120 and signal sensor. The pulsegenerator 1120 and signal sensor contains electronics to sense variouselectrical signals of a heart 1110 and also produce current pulses fordelivery to the heart 1110.

[0076] The lead 1100 includes a lead body 1115, an elongate conductor1116 contained within the lead body 1115, and at least one electrodeassembly 1130. In one embodiment, the electrode assembly 1130 isdisposed proximate to the distal end 1102 of the lead 1100. In anotherembodiment, the electrode assembly 1130 is disposed between the distalend 1102 and the proximal end 1104 of the lead 1100, at an intermediateportion 1103 of the lead 1100. The lead body 1115 is covered by abiocompatible insulating material. Silicone rubber or other insulatingmaterial are examples of materials which are used for covering the leadbody 1115.

[0077] The elongate conductor 1116 defines a lumen 1217 therein (FIG.12) and is adapted to receive a stiffening stylet that extends throughthe length of the lead 1100. The stylet stiffens the lead 1100, and canbe manipulated to introduce an appropriate curvature to the lead 1100.The manipulation of the stylet facilitates the insertion of the lead1100 into and through a vein and through an intracardiac valve toadvance the distal end 1102 of the lead 1100 into, for example, aventricle of the heart 1110. A stylet knob is coupled with the styletfor rotating the stylet, advancing the conductor into tissue of theheart, and for manipulating the lead 1100.

[0078] The electrode assembly 1130 is adapted to be coupled with tissue,for example, within a heart 1110 or in a vein. In one embodiment, theelectrode assembly 1130 includes a plurality of conductive tines 1120and at least one defibrillation electrode 1132. In another embodiment,the defibrillation electrode 1132 extends to the distal end 1102 of thelead 1100, where the defibrillation electrode 1132 is disposed at adistal tip 1104 of the lead 1100. In yet another embodiment, as shown inFIG. 11B, the electrode assembly 1130 includes a plurality ofdefibrillation electrodes 1133.

[0079]FIG. 12 illustrates another embodiment of an electrode assembly1230, which includes at least one distal defibrillation electrode 1232.The distal defibrillation electrode 1232 is disposed at a distal tip1202 of a lead 1200, where the defibrillation electrode 1232 is adaptedto provide defibrillation shocks at the distal tip 1202 of the lead1200. The electrode assembly 1230, in another embodiment, includes aproximal defibrillation electrode 1240. The proximal defibrillationelectrode 1240 is electrically common with the distal defibrillationelectrode 1232. In one embodiment, the tip 1233 of the defibrillationelectrode 1232 has a smaller diameter than the proximal defibrillationelectrode 1240, which accommodates pacing and sensing electrodes,discussed further below, without significantly increasing the profile ofthe lead 1200. Having the defibrillation electrode 1232 disposed at thedistal tip 1202 allows for the defibrillation electrode 1232 to bepositioned to the further possible extent within an apex 1111 (See FIG.11A) of the heart 1110. It is believed that positioning thedefibrillation electrode 1232 in this position assists in producing afavorable electric field distribution through the ventricular muscle,which lowers the shock strength requirement for defibrillation of theheart 1110.

[0080] The electrode assembly 1230 further includes a plurality ofconductive tines 1220. The conductive tines 1220, in one embodiment,comprise sensing and pacing electrodes. The tines 1220, in anotherembodiment, comprise slender projections which project away from thelead body 1215. In one embodiment, three conductive tines 1220 extendfrom the lead body 1215, as shown in FIG. 13. Insulation 1217 isdisposed between the defibrillation electrode 1232 and the conductivetines 1220, for instance, silicone rubber, which prevents the electrodesurface of the conductive tines 1220 from contacting the defibrillationelectrode 1232. In one embodiment, a conductive member 1234, whichserves as an electrode, is disposed on a distal tip 1226 of each of thetines 1220. In another embodiment, the conductive member 1234 isdisposed on other portions of the tines 1220. In one embodiment, theconductive member 1234 is mechanically coupled with the tines 1220.

[0081] Disposed within each of the tines 1220 is a conductive element1221 formed of a conductive material, for example, a metal wire.Alternatively, in another embodiment, the conductive element 1221 isformed of a flat wire or a foil. The conductive element 1221 iselectrically coupled with a conductor coil 1216, for instance, bywelding, crimping, or by conductive adhesive. In addition, theconductive element 1221 is electrically coupled with the conductivemember 1234, and forms the electrical connection between the conductivemember 1234 and the conductor coil 1216, which allows for the tines 1220to be conductive. The conductive member 1234 of the conductive tines1220 is adapted to contact tissue of a body in which the lead 1200 isimplanted, and the member 1234 is adapted to sense and/or pace thetissue. In addition, the conductive tine 1220 assists in physicallyfixating the lead 1200 with tissue, for example within a vein or artery.It should be noted that variations to the conductive tines 1220,include, but are not limited to, the embodiments discussed above andbelow.

[0082]FIGS. 14A and 14B illustrate another embodiment of an electrodeassembly 1430 of a lead 1400. The electrode assembly 1430 is similar tothat described above for FIGS. 12 and 13, and common elements are notrepeated. The electrode assembly 1430 further includes a portion 1436between a proximal defibrillation coil 1440 and a distal defibrillationcoil 1432. The portion 1436 forms an electrical discharge surface forthe defibrillation shock. Insulation 1416 is disposed between conductivetines 1420 and a lead body 1410 which covers the portion 1436 formingthe electrical discharge surface for a defibrillation shock. In oneembodiment, the shocking portion 1436 is exposed in three locations, 120degrees apart, as shown in FIG. 14B.

[0083]FIG. 15 illustrates an embodiment of a lead 1500 including anelectrode assembly 1530. The electrode assembly 1530, in one embodiment,comprises at least one defibrillation electrode 1532. In anotherembodiment, the electrode assembly 1530 includes a pacing and/or sensingelectrode, as discussed and shown above. The lead 1500 includes a leadbody 1515, which is formed of a biocompatible insulating material, forexample silicone rubber. A conductive material 1502 is disposed over theelectrode assembly 1530, which facilitates the electrical connectionbetween tissue which is to be stimulated and the electrode assembly1530.

[0084] In one embodiment, the conductive material 1502 comprisesconductive polymer, elastomer, or rubber which is molded over theelectrode assembly 1530. The conductive material 1502, in anotherembodiment, comprises a sheath 1534 of conductive material. In anotherembodiment, the conductive material 1502 comprises, although is notlimited to, any of the following: conductive polymers, rubbers, orelastomers like conductive silicone rubber and conductive thermoplasticelastomers like polyurethane elastomers, polyether-ester elastomers, andpolyetheramide elastomers. In another embodiment, the conductivematerial 1502 comprises a combination of materials. In yet anotherembodiment, the electrode assembly 1530 is made from a conductivematerial including, but not limited to conductive polymers, rubbers, orelastomers like conductive silicone rubber and conductive thermoplasticelastomers like polyurethane elastomers, polyether-ester elastomers, andpolyether-amide elastomers.

[0085] A lead 1600 of another embodiment is illustrated in FIGS. 16A and16B. The lead 1600 includes an electrode assembly 1630 which has aconductive fixation feature 1660. The conductive fixation feature 1660is adapted to send and/or receive signals from a heart. In addition, theconductive fixation feature 1660 fixates the lead 1600 within a body. Inone embodiment, the conductive fixation feature 1660 is adapted to sendand/or receive signals in conjunction with additional electrodes, asdiscussed above.

[0086] The conductive fixation feature 1660 extends from a first end1662, which is fixed to a lead body 1615, to a second end 1664 which ismovably coupled with the lead body 1615. An intermediate portion 1666comprises a flexible conductive portion 1668. The flexible conductiveportion 1668 is adapted to flex away from the lead body 1615 as thesecond end 1664 is moved toward the first end 1662, as shown in FIG.16B. To deploy the conductive fixation feature 1660, a wire 1670 isdisposed within the lead 1600 and pushed towards the second end 1664 ofthe conductive fixation feature 1660. In another embodiment, anotherdeployment mechanism, such as a slide tube, is used to deploy theconductive fixation feature 1660 into a flexed position. As the secondend 1664 is moved toward the first end 1662, the intermediate portion1666 bows as it flexes away from the lead body 1615. As the conductivefixation feature 1660 is deployed, the overall diameter of theconductive fixation feature 1660 increases until it engages, forexample, a vein 1680 to fixate the lead 1600 therein.

[0087] In one embodiment, the electrode assembly 1630 further includes alocking mechanism 1650 which maintains the conductive fixation feature1660 in a flexed position. The locking mechanism 1650, in oneembodiment, includes a slider 1652 which engages within an interferenceslot 1654. The slider 1652 is coupled with the second end 1664 of theconductive fixation feature 1660 and slides within a slot 1656 disposedwithin the lead 1600. The slider 1652 freely slides within the slot 1656unless it is engaged by the interference slot 1654, which provides aninterference fit between the slider 1652 and the interference slot 1654.Once the slider 1652 is engaged with the interference slot 1654, theintermediate portion 1666 of the conductive fixation feature 1660 flexesaway from the lead body 1615 into the vein 1680 to fixate the lead 1600therein.

[0088]FIGS. 17A and 17B illustrate yet another embodiment of a lead1700. The lead 1700 includes a lead body 1715 and an electrode assembly1730 which has a conductive fixation feature 1760. The conductivefixation feature 1760 is adapted to send and/or receive signals from aheart. In addition, the conductive fixation feature 1760 fixates thelead 1700 within a body. The conductive fixation feature 1760 iselectrically coupled with a conductor 1716 disposed within the lead body1715. In one embodiment, the conductive fixation feature 1760 comprisesa stent conductor 1761. In another embodiment, the conductive fixationfeature 1760 is adapted to send and/or receive signals in conjunctionwith additional electrodes, as discussed above.

[0089] The conductive fixation feature 1760 extends from a first end1762 to a second end 1764, and includes an intermediate portion 1766therebetween. The intermediate portion 1766 comprises a flexibleconductive portion 1768 which is adapted to flex away from the lead body1715 when the conductive fixation feature 1760 is deployed, as shown inFIG. 17B. To deploy the conductive fixation feature 1760, a ballooncatheter 1780 is disposed within the lead 1700. As the balloon catheter1780 is expanded, as shown in FIG. 17B, the intermediate portion 1766bows as it flexes away from the lead body 1715. The overall diameter ofthe conductive fixation feature 1760 increases until it engages a veinto fixate the lead 1700 therein.

[0090] Advantageously, the conductive tines aid in providing animplantable medical device which allows for fixation of a the medicaldevice within tissue, such as a vein or artery. A further benefit isthat the fixation feature includes an electrode which can sense or pacethe tissue to which it is fixated. The conductive fixation feature alsoprovides resistance to inadvertent dislodgment of the medical devicefrom the patient.

[0091] It is believed that positioning the defibrillation electrode atthe distal portion of the lead assists in producing a favorable electricfield distribution through the ventricular muscle, which lowers theshock strength requirement for defibrillation. The combination of thedefibrillating electrode and the pacing/sensing electrode disposed onconductive tines allows for the pacing/sensing electrodes to be disposedproximate to the distal end of the lead, yet are sufficiently spacedfrom the defibrillating electrode to avoid sensing problems following ashock from the defibrillation electrode.

[0092] It is to be understood that the above description is intended tobe illustrative, and not restrictive. Although the use of the lead hasbeen described for use in a cardiac pacing system, the lead could aswell be applied to other types of body stimulating systems. It should benoted that features of the various above-described embodiments may beinterchanged to form additional combinations. Many other embodimentswill be apparent to those of skill in the art upon reviewing the abovedescription. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A lead assembly comprising: a lead body extendingfrom a distal end to a proximal end and including a conductor disposedtherein; an electrode assembly including at least one electrode, theelectrode assembly electrically coupled with the conductor; and theelectrode assembly including at least one electrically conductive tineadapted for fixating the lead assembly within tissue, the at least oneelectrically conductive tine electrically coupled with the electrodeassembly.
 2. The lead assembly as recited in claim 1, wherein the atleast one electrically conductive tine has a first end coupled with thelead body and a second end which extends away from the lead body.
 3. Thelead assembly as recited in claim 1, wherein the at least one tine isformed of electrically conductive material.
 4. The lead assembly asrecited in claim 3, wherein the electrically conductive materialcomprises a conductive polymer.
 5. The lead assembly as recited in claim3, wherein the electrically conductive material comprises a conductivesilicone rubber.
 6. The lead assembly as recited in claim 3, wherein theelectrically conductive material comprises a conductive thermoplasticelastomer.
 7. The lead assembly as recited in claim 1, wherein the atleast one conductive tine includes a conductive coating thereon.
 8. Thelead assembly as recited in claim 1, wherein the at least one conductivetine is molded to the conductor.
 9. The lead assembly as recited inclaim 1, wherein the lead assembly includes a plurality of conductivetines.
 10. The lead assembly as recited in claim 1, wherein the at leastone electrically conductive tine comprises a wire extending away fromthe lead body.
 11. The lead assembly as recited in claim 1, wherein theat least one conductive tine comprises a flat wire extending away fromthe lead body.
 12. The lead assembly as recited in claim 1, wherein theat least one conductive tine comprises a foil extending away from thelead body.
 13. The lead assembly as recited in claim 1, furthercomprising at least one non-conductive tine adapted for fixating aportion of the lead assembly.
 14. The lead assembly as recited in claim1, further comprising a defibrillation electrode disposed at the distalend of the lead body.
 15. The lead assembly as recited in claim 1,wherein the at least one conductive tine is retractable toward theconductor.
 16. A lead assembly comprising: a lead body extending from adistal end to a proximal end and including a conductor disposed therein;an electrode assembly including at least one electrode, the electrodeassembly electrically coupled with the conductor; and the at least oneelectrode including at least one electrically conductive cone adaptedfor fixating the lead assembly within tissue, the at least oneelectrically conductive cone electrically coupled with the electrodeassembly.
 17. The lead assembly as recited in claim 16, wherein the coneincludes a conductive ring disposed on a distal end of the cone.
 18. Thelead assembly as recited in claim 16, wherein the conductive cone isformed of a conductive polymer.
 19. A lead assembly comprising: a leadbody extending from a proximal end to a distal end including a conductordisposed therein; an electrode assembly including at least one electrodeelectrically coupled with the conductor, the electrode assembly coupledwith the lead body; at least one conductive tine coupled with a portionof the lead body; and a conductive member disposed within a portion ofthe at least one tine, the conductive member electrically coupled withthe electrode assembly.
 20. The lead assembly as recited in claim 19,wherein at least one tine is partially covered with non-conductivematerial.
 21. The lead assembly as recited in claim 19, wherein the atleast one tine extends from a first end proximate the lead body to asecond end disposed away from the lead body.
 22. The lead assembly asrecited in claim 19, wherein the lead assembly includes a plurality ofconductive tines.
 23. The lead assembly as recited in claim 19, whereinthe conductive member comprises a wire.
 24. The lead assembly as recitedin claim 19, wherein the conductive member comprises a flat wire. 25.The lead assembly as recited in claim 19, wherein the conductive membercomprises a foil.
 26. The lead assembly as recited in claim 19, whereinthe at least one tine extends from a first end proximate the lead bodyto a second end disposed away from the lead body, and a conductive capis disposed at the second end of the at least one tine.
 27. The leadassembly as recited in claim 19, further comprising at least onenon-conductive tine adapted for fixating a portion of the lead assemblywithin tissue.
 28. A lead assembly comprising: a lead body extendingfrom a proximal end to a distal end defining an intermediate portiontherebetween; and at least one conductive fixation feature extendingaway from the lead body at an angle of less than ninety degrees, the atleast one conductive fixation feature coupled with the intermediateportion of the lead body and adapted for fixating the lead assemblywithin a vein, at least one conductive fixation feature including anelectrode.
 29. The lead assembly as recited in claim 28, wherein theelectrode comprises a sensing or pacing electrode.
 30. The lead assemblyas recited in claim 28, wherein the at least one conductive fixationfeature comprises a conductive tine.
 31. The lead assembly as recited inclaim 28, wherein the at least one conductive fixation feature comprisesa wire.
 32. The lead assembly as recited in claim 28, wherein the atleast one conductive fixation feature comprises a slender projectionextending from a first end proximate the lead body to a second enddisposed away from the lead body at an angle.
 33. The lead assembly asrecited in claim 32, further comprising a conductive cap is disposed atthe second end of the at least one tine.
 34. The lead assembly asrecited in claim 28, further comprising at least one non-conductive tineadapted for fixating a portion of the lead assembly within tissue. 35.The lead assembly as recited in claim 28, wherein the at least oneconductive fixation feature comprises a cone.
 36. A lead assemblycomprising: a lead body extending from a proximal end to a distal enddefining an intermediate portion therebetween; at least one conductordisposed within the lead body and extending from a first end to a secondend, the first end proximate to the proximal end of the lead body andthe second end proximate to the distal end of the lead body; and adefibrillation electrode electrically coupled with the conductor, thedefibrillation coil disposed at the second end of the conductor forminga defibrillation tip at the distal end of the lead body; at least oneelectrically conductive tine coupled with a portion of the lead body.37. The lead assembly as recited in claim 36, further comprising asecond defibrillation coil disposed at the intermediate portion of thelead body.
 38. The lead assembly as recited in claim 36, wherein the atleast one conductive tine has a first end coupled with the lead body anda second end which extends away from the lead body.
 39. The leadassembly as recited in claim 36, wherein the at least one tine ispartially covered with non-conductive material.
 40. The lead assembly asrecited in claim 38, further comprising a conductive bead coupled withthe second end of the conductive tine.
 41. The lead assembly as recitedin claim 40, wherein the conductive bead is welded with the conductivetine.
 42. The lead assembly as recited in claim 36, wherein the at leastone conductive tine is adapted for sensing and/or pacing.
 43. The leadassembly as recited in claim 42, wherein the at least one conductivetine is electrically common with the defibrillation electrode.
 44. Thelead assembly as recited in claim 36, wherein the defibrillationelectrode is defined by a first diameter proximate the distal end of thelead body and the conductor is defined by a second diameter proximate tothe proximal end of the lead body, and the first diameter is smallerthan the second diameter.
 45. The lead assembly as recited in claim 36,further comprising an electrical discharge surface between the seconddefibrillation coil and the distal defibrillation tip.
 46. The leadassembly as recited in claim 36, further comprising a defibrillationcoil disposed at the intermediate portion of the lead body, anelectrical discharge surface between the defibrillation coil and thedistal defibrillation tip, and insulation disposed between the at leastone conductive tine and the defibrillation coil.
 47. A lead assemblycomprising: a lead body extending from a distal end to a proximal endand including a conductor disposed therein; an electrode assemblyincluding at least one electrode, the electrode assembly electricallycoupled with the conductor; and the at least one electrode assemblyincluding a plurality of electrically conductive tines adapted forfixating the lead assembly within tissue, the plurality of electricallyconductive tines electrically coupled with the electrode assembly andadapted to send and receive electrical signals, and the conductive tinesare retractable toward the conductor.
 48. The lead assembly as recitedin claim 47, each of the conductive tines extending from a hinge pointto a distal point, the conductive tines adapted to flex at the hingepoint.
 49. The lead assembly as recited in claim 47, the lead bodyincluding a lumen therethrough, the retractable tines disposed withinthe lumen in a first position.
 50. The lead assembly as recited in claim49, the retractable tines extended out of the lumen in a secondposition.
 51. A lead assembly comprising: a lead body extending from adistal end to a proximal end and including a conductor disposed therein;an electrically conductive fitting coupled with the conductor; anelectrode assembly including at least one electrode, the electrodeassembly electrically coupled with the fitting; and the at least oneelectrode assembly comprising at least one conductive tine molded to thefitting, the at least one tine adapted for fixating the lead assemblywithin tissue and adapted to send and receive electrical signals. 52.The lead assembly as recited in claim 51, wherein the at least one tineis formed of a conductive polymer.
 53. The lead assembly as recited inclaim 51, wherein the at least one tine is formed of a conductivethermoplastic elastomer.
 54. The lead assembly as recited in claim 51,wherein the at least one tine is formed of a conductive silicone rubber.55. A lead assembly comprising: a lead body extending from a distal endto a proximal end and including a conductor disposed therein; anelectrode assembly including at least one electrode, the electrodeassembly electrically coupled with the conductor; the at least oneelectrode assembly including a conductive fixation feature which isadapted to send and receive electrical signals; the conductive fixationfeature extending from a first end to a second end including a flexibleand conductive intermediate portion therebetween, the intermediateportion flexible away from the conductor; and the first end of theconductive fixation feature attached to the lead body and the second endis movably coupled with the lead body.
 56. The lead assembly as recitedin claim 55, further comprising a locking mechanism, the lockingmechanism adapted to maintain the intermediate portion in a flexedposition.
 57. The lead assembly as recited in claim 56, the lockingmechanism comprising a slider movably disposed within a slot, and aninterference slot sized to engage the slider, the slider coupled withthe second end of the conductive fixation feature.
 58. The lead assemblyas recited in claim 55, further comprising a deployment mechanism. 59.The lead assembly as recited in claim 58, wherein the deploymentmechanism comprises a wire.
 60. A lead assembly comprising: a lead bodyextending from a distal end to a proximal end and including a conductordisposed therein; an electrode assembly including at least oneelectrode, the electrode assembly electrically coupled with theconductor; and a sheath of conductive material disposed over theelectrode assembly.
 61. The lead assembly as recited in claim 60,wherein the electrode assembly comprises a defibrillation coil.
 62. Thelead assembly as recited in claim 60, wherein the sheath of conductivematerial is formed of a conductive polymer.
 63. The lead assembly asrecited in claim 60, wherein the sheath of conductive material is formedof a conductive thermoplastic elastomer.
 64. The lead assembly asrecited in claim 60, wherein the sheath of conductive material is formedof conductive silicone rubber.
 65. A system for delivering signals tothe heart, the system comprising: an electronics system including acardiac activity sensor and a signal generator for producing signals tostimulate the heart; and a lead assembly including: a lead bodyextending from a distal end to a proximal end and including a conductordisposed therein; an electrode assembly including at least oneelectrode, the electrode assembly electrically coupled with theconductor; and the at least one electrode assembly including at leastone electrically conductive tine adapted for fixating the lead assemblywithin tissue, the at least one electrically conductive tineelectrically coupled with the electrode assembly, wherein the at leastone tine has a first end coupled with the lead body and a second endwhich extends away from the lead body.
 66. The system as recited inclaim 65, wherein the at least one tine is formed of a conductivepolymer.
 67. The system as recited in claim 65, wherein the at least onetine is formed of a conductive elastomer.
 68. The system as recited inclaim 65, wherein the at least one conductive tine includes a conductivecoating thereon.
 69. The system as recited in claim 65, wherein the atleast one conductive tine comprises a wire extending away from the leadbody.
 70. The system as recited in claim 65, wherein the at least oneconductive tine extends from a first end proximate the lead body to asecond end disposed away from the lead body, and a conductive cap isdisposed at the second end of the at least one tine.
 71. The system asrecited in claim 65, further comprising at least one nonconductive tineadapted for fixating a portion of the lead assembly within tissue.
 72. Amethod comprising: disposing a defibrillation electrode tip on a distalend of a lead body, the lead body extending from a proximal end to thedistal end and having an intermediate portion therebetween; coupling atleast one conductive tine with the intermediate portion of the leadbody; positioning the defibrillation electrode tip within an apex of aheart; coupling the lead body to a pulse generator; and deliveringdefibrillation shocks from the pulse generator via the defibrillationelectrode tip.
 73. The method as recited in claim 72, further comprisingpacing the heart with the at least one conductive tine.
 74. The methodas recited in claim 72, further comprising sensing the heart with the atleast one conductive tine.
 75. The method as recited in claim 72,further comprising providing insulation between the defibrillationelectrode tip and the at least one conductive tine.
 76. The method asrecited in claim 72, further comprising disposing a conductive member ona distal tip of each conductive tine.
 77. The method as recited in claim72, further comprising coupling a conductive member to the at least oneconductive tine.
 78. A lead comprising: a lead body extending from aproximal end to a distal end and having an intermediate portiontherebetween; a first defibrillation electrode tip disposed at thedistal end of the lead body and adapted to deliver defibrillation shocksat the distal end of the lead body; a second defibrillation electrodedisposed at the intermediate portion of the lead body and adapted todeliver defibrillation shocks at the intermediate portion of the leadbody; and at least one conductive tine disposed at the intermediateportion.
 79. The lead as recited in claim 78, wherein the defibrillationelectrode tip has a first outer diameter, the second defibrillationelectrode has a second outer diameter, and the first outer diameter isless than the second outer diameter.
 80. The lead as recited in claim78, wherein the at least one conductive tine includes a flat wire. 81.The lead as recited in claim 78, wherein the at least one conductivetine includes a foil.
 82. The lead as recited in claim 78, wherein theat least one conductive tine includes a conductive element, the leadbody includes a coil, and the lead includes a means for coupling theconductive element with the coil.